I am interested to see how other people have installed electrics in their 501X, so feel free to post photos!
This layout seemed the best for me, the servo and ESC receiver leads both go under the antenna mount, so are away from the belt.
Obviously its not quite finished yet, I am waiting on some wire for the esc and cells
There should be room for a large ESC on the right hand side there but it would need to be velcro'd in place since you need access to the motor screws (unless its brushless, in which case I guess not!)